Arc-current regulator



J. A. HOLIFIELD. ARC CURRENT REGULATOR. APPLICATION FILED NOV. 20, 1919.

Patented May 9, 1922.

INVENTOR v Mfiz/F/em BY ATTQRNEY supplement the loss the motor may be JOSEPH A. HOIJFIELD, OF MOBILE, ALABAMA ARC-CURRENT REGULATOR.

Specification of letters Patent. Application filed November 2c, 1919. Serial No.

To all whom it may concern:

Be it known that I, JOSEPH ANDREW HoLI- FIELD, a citizen of the United States of America, residin at Mobile, in the county of Mobile and tate of Alabama, have invented certain new and useful Improvements in Arc-Current Regulators, of which the following is a specification.

l\ y invention relates to current regulators for arcing circuits and is especially adapted for regulating the circuits of arc welding apparatus.

The purpose of my invention is to obtain an even and smooth regulation of the current so that the welding range of voltage desired ing esired arc.

It is my purpose'especially to accomplish these ends by an apparatus which is small and inexpensive and which is capable of being readily transported by hand as it will only wei h about 126 pounds for a'lOOampere out t. i

y invention is based upon the arrangement of a resistance preferably adjustable in series with the fields of and of the arc electrodes, the resistance and fields being capable of carrying the full arc load and the armature of the motor being connected 1n a shunt or by-pass circuit across the field circuit. With the resistance set at say to carry 100 amperes, upon the short circuiting of the are, only 100 amperes will flow through the resistance and fields plus what little current may pass through the armature which revolves in a highly magnetic field, but when the arc is drawn e resistance in the field circuit is increased and there will be a resultant drop in amperage which weakens the field and causes the counter E. M. F. in the armature by-pass to fall, permitting the necessary increase in amperage to flow th through the field and resistance circuit. In this manner, as the load at the arc rises and falls there is an automatic, instantaneous and perfect compensation between the fixed resistance in the field circuit and the varying counter E in the armature by-pass circuit. As a result of my arrangement, the size of small, inexpensive and readily transportable, and by avoiding the use of a choke coil practice or for the maintenance of the a regulating motor' rough the by-pass to trated in Fig. 1, I show reduced to one which is Patented May 9, 1922.

I am enabled to reduce the costand weight of the apparatus about 7 5 per cent. It is not material to the purposes of my invention in what manner the resistance and the motor fields are connected so long as they are arranged in series with the are, leaving the armature in a by-pass or shunt circuit and adapting the arc to draw the requisite sup- 'ply of currentin varying quantlties as the arc load fluctuates t rough the parallel field and armature circuits. It is contemplated that the motor will e provided with some suitable mechanical or electro-magnet brake or speed governor which will permit it when the arc is struck to run practically free so as to generate the maximum counter E. M. F but which will automatically restrain the tendency of the motor to speed up as the arc is lengthened so that the counter F. will fall proportionately to the flow of current needed through the by-pass to maintain the uniform amperage at the arc.

In the accompanying drawings I have illustrated several embodiments of my invention diagrammatically:

Fig. 1 illustrates diagrammatically one arrangement of my invention in which the shunt circuit in the armature is branched across the field circuit so that the current flowing through the armature shunt will not flow through the fields.

In'Fig. 2 I show a modified arrangement in which the current flowing throughv the armature shunt circuit also flows through the field and thus modifies the magnetism of the fields.

Fig. 3 shows the armature shunt circuit including a differentially wound field coil to weaken the field.

Figs. 4, 5 and 6 are diagrammatic charts illustrating the varying regulating functions throughout the elastic limits of the arc i for the three types of apparatus illustrated respectively in Figs. 1, 2 and 3.

Figs. 7 and 8 show side and end views of a typical automatic speed governor for my regulating motor.

Similar reference numerals refer to similar parts throughout the drawings.

In the embodiment of my invention illus diagrammatically circuits in which D. C. current flows from a the positive main line wire 1 to the negative main line wire 2 through a branch or'arc circuit 3 which includes in able resistance 4, the field coils 5 of a series series the adjust-' motor 6, and the arcing electrodes 7 and 8, which are typical of any suitable electrodes for welding, are lights, or equivalent purposes. The armature 9 of the motor is connected in a by-pass or a shunt circuit 10 across the branch circuit 3 and parallel with the fields.

In Fig. 2 the D. (7. current flows from the positive line 1 through the are circuit 3 and in series through the field coils 5, the adjustable resistance 4 and the are, the armature 9 being arranged in a shunt or by-pass circuit 11 connected in series and not in parallel with the fields.

In Fig. 3 the current flows from the main 1 through the branch circuit 3 passing in series'through the adjustable resistance 4, the are, and the field coils 5, the shunt or bypass circuit 12 including field coils 13 differentially wound over the field coils 5 and in series with the armature 9.

In Fig. 7 the motor 6 is formally illustrated, having its armature shaft 14 provided with a disk 15 having hinged arms 16 carrying brake shoes 1'? adapted to move outwardly responsive to predetermined centrifugal force, in doing which the arms overcome the action of tension springs 18 which under normal speed conditions hold back the brake shoes from engaging a brake band 19 attached by suitable brackets 20 to the motor casing. This brake, which is described more in detail in my pending application, Serial No. 304,988, will. function automatically to maintain the speed of the motor substantially constant under normal arc load variations. It will be understood that any other well known type of magnetic or mechanical brake or automatic speed governor capable of functioning to the end and for the purposes described, may be employed.

It is important to note that the adjustable resistance. 4 and the field coils 5 should be capable of carrying the amperage required for full load conditions at the arc, say 100 amperes. In my former application, a series motor with an automatic speed regulator,

was arranged with its field and armature in series with a choke coil and the arc and it regulated the current flowing through the arc by the generation of counter E. M. F. or bucking current, the arc load being automatically varied according to the varying strength of the motors magnetic circuit and the resistance across the are, thereby causing a predetermined current to flow througli the are circuit which is stabilized by the choke or reaction coils and held constant by the counter F. or the bucking reaction of the motor armature. In my present invention a by-pass is provided in which the same regulating function is had but only in respect of the excess current forced through the by=pas y he resistance in the field circuit, for the main volume of current will always flow around the armature through the fields and resistance to the arc. The flow of the current through the by-pass serves to excite the motor fields at all times "0 after the arc is drawn and as the arc grows longer the resistance in the main by-pass circuit increases, causing the magnetism in the fields to fall, whereupon the counter E. M. F. of the armature falls and there will be increased flow of current through the by-pass circuit which will replace that which is lost by the resistance to the flow of current across the arc. There are thus compensating functions derived from the varying resistance in the series field circuit and the varying counter E. of the arma ture shunt or by-pass circuit, which together secure and maintain a constant current of uniform amperage from a short circuit to 4 the arc limit at all times and under all conditions. By the provision of this armature bypass and variable resistance in the field circuit, I am able to get the regulating function of the counter E. M. F. from the armature of a small, light and inexpensive motor. In practice I am using a 1 H. P. 32 volt high speed motor in a 100 ampere welding set, and its duty is to replace the approximate loss' of 35' amperes between the minimum and maximum length of the arc. Also by dispensing with the heavy and expensive choke coil used with my series motor regulating set,-I further reduce the cost and weightof my equipment approximately 75 per cent, while gaining greater smoothness and reliability of regulation. The resistance as connected in relation to the field coils in Fig. 1 is more sensitive and satisfactory than as connected in Fig. 2 because the compensating flow of current drawn through .the armature by-pass does not affect the magnetism of the fields. This will be apparent by reference to Figs. 4 and 5, where the diagram in Fig. 4 shows a constant amperage at the arc maintained throughout the elastic limit of the arc, whereas in Fig. 5, the current drawn through the armature bypass maintains the magnetism of the fields so that the amperage at the arc tends to drop gradually as the are is lengthened until only about 75 amperes are flowing at the limit of the arc. This may be of advantags in delicate work such as welding fire cracks in boilers where the weld is to be cooled or the arc temperature reduced by drawing a longer are. The most sensitive arrangement is that shown in Fig. 3, where the differentially wound field coils tend to increasingly weaken the field proportionately to the flow ofcurrent through the bypass, thereby gradually increasing the amperage at the are, as seen in the chart, Fig. 6. This arrangement gives a quicker or more Sensitive regulation and provides a greater heat at the limit of the arc when such is needed.

One great advantage of my apparatus as illustrated in Fig. 1, where the uniformity of heat or amperage at the weld is automatically maintained constant, isthat the welding can be done by unskilled operators, the apparatus functioning instantaneously and automatically to preserve a uniform elastic limit and thus it being unnecessary for a highly skilled operator to maintain a uniform length of arcin making theweld.

In accordance with therequirements of law, I have illustrated several preferred types of apparatus embodying my invention, but I desire it to be understood that those skilled in the art may variously modify the structure and arrangement ofparts without departing from the especially novel principle upon which my invention is based.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. In an electric welding apparatus, a

welding circuit having electrodes therein.-

means to interpose a resistance in the welding circuit, a by-pass circuit around said resistance, means to oppose a counter E. M. F. to the flow of current through the by-pass, and means to vary said counter E. M. F. automaticallv and directly responsive to the resistance o the arc.

2. In an electric welding apparatus, a welding circuit having electrodes therein, means to interpose an adjustable resistance in the welding circuit, a by-pass circuit around said resistance, means to oppose acounter E. M. F. to the flow of current through the by-pas's, and means to vary said counter E. M. F. automatically responsive to the flow of current past said resistance to maintain uniform amperage at the are.

n apparatus for regulating an arcing current comprising a substantially constant speed motor having its armature circuit and its field circuit in parallel with each other and in series with the arc, and a resistance capable of carrying the full arc load in series with the field circuit.

4. An apparatus. for automatically regulating an arcing current which includes a substantially constant speed motor with its fields in serieswith and capable of carrying the full load of the arc, and a resistance also capable of carrying the full arc load in series with the motor fields, the motor armature being in a by-pass circuit across the field circuit.

5. In a welding ap trical energy, a we aratus, a source of elecding circuit including arcing electrodes, a regulating motor comprising fields and an armature, an adjustable resistance in series with the motor fields, and a shunt or by-pass circuit for the motor armature. V

6. A welding apparatus comprising, incombination, arcing electrodes, a motor having an automatic speed governor, a resistance, the motor fields and the resistance being adapted to ass the maximum required amperage for e are, a circuit connecting the field coils, resistance and arc electrodes in series, and a by-pass circult connecging the motor armature in shunt to said 75 fiel s.

7. The combination with an electriecircuit carrying direct current, of a welding circuit branched on the first named circuit, a motor in series with and its having its field coils armature in shunt across the field circuit, a governor for controlling the speed of the motor, and an adjustable resistance in the series with the motor fields.

8. The combination with a direct current circuit, of a welding circuit branched therefrom, a motor for the welding circuit driven by the current in said circuit and having its armature in shunt to it fields and the armature and fields in series with said welding circuit, and an adjustable resistance capable of carrying the maximum amperage required for the welding circuit arranged in series with motor fields and in shunt to the armature. In testimony whereof I afiix my signature.

JOSEPH A. HOLIFIELD.

(Witness Norm: Wmsn. 

